1. Field of Invention
The invention relates generally to a method and system for detecting grids in a digital image.
2. Background of the Related Art
There are methods and systems, which are well known in the art, for viewing internal portions of an object by directing radiation signals, generally referred to in the art as x-rays, onto the object and by receiving the radiation signals which pass through the object onto a recording medium, typically film. Ideally, the radiation signals will pass from the radiation source to the film in a straight line. However, as the radiation signals pass through the object, some of the signals are scattered so that they no longer travel in a straight line, which scattering causes reduced image quality. To reduce this effect, radiographic grids are placed between the object and film. Radiation grids are lead foil strips placed in a spaced apart relationship with each other, which spaced apart relationship is typically maintained by placing aluminum between the strips. The strips and aluminum are then packaged in a suitable covering. These grids, though effective for reducing radiation scattering, occasionally introduce artifacts such as grid lines into the image.
The film containing the captured image is processed in a variety of well known and utilized techniques for permitting on observer to view the image captured on the film. One such technique is to convert the image into a digitized form for displaying the image on a computer display and similar devices.
To convert the image into digitized form, typically, a digitizer converts the film into digital form for permitting the image to be displayed on a computer display by well known techniques.
Before displaying the image on the computer screen, grids lines, if there are any, should be removed. There are two well known methods in the art for reducing the effects of grid lines. One method utilizes moving the grids when the object of interest is radiated. The other method is to apply a processing algorithm to the computer system which is displaying the image.
Although the above methods for reducing grid lines are satisfactory, they are not without drawbacks. Moving grids involve a costly procedure and, in addition, require the object to be exposed to the radiation for a longer period of time than is normally required. This obviously is a drawback if the object is a person. For these reasons, they are not a preferred method of reducing the effects of grid lines. The processing algorithm is also costly and, as a secondary effect, can reduce the quality of the image.
Consequently, a need exists for a method of detecting grids so that costly processing algorithms for removing grids are applied only when there are grids in the image.